High pressure or pressurized systems are typical in hydrolysis and pre-hydrolysis processes. Feeding of cellulosic biomass material including annual plants to be treated in a treatment arrangement, for example, an arrangement for a pre-hydrolysis process therefore often involves handling of the material under higher pressures. In such arrangements it is important to provide a smooth and reliable feeding of the biomass material in order to prevent and avoid, for example, uneven power consumption and problems with so called blow-back flow.
According to prior art solutions, biomass material is transported to the treatment process via a feeding arrangement such as a pin drum feeder and further to a conveying device which conveys the material to the treatment process.
In typical prior art feeding arrangements, a housing is arranged with an upper inlet opening for receiving the material and a lower outlet opening 15 for discharging the material to conveyor. Revolving drums are provided in the housing to control the transport and flow rate of the material through the housing. After the material has passed the revolving drums, the material falls through the lower outlet opening to the plug screw feeder. It is important to maintain a smooth and continuous flow of material into the treatment process. This is crucial in pressurized systems. An example of a process in a pressurized system is a pre-hydrolysis process. Such processes are sensitive to changes in the flow rate. The material is fed to the pin drum feeder from a vertical feeding chute or similar unit connected to the upper inlet opening of the housing. An effective and smooth average flow of material into the pin drum feeder requires that this vertical feeding pipe is completely filled with material during operation. Hence, when the feeding pipe is completely filled with material, the flow into the pin drum feeder will be smooth and continuous. The revolving drums operate to feed the material through the housing towards the outlet opening in a controlled manner. During the rotation of the drums material is forced through the housing and leaves the drums when the weight of the material exceeds the binding strength of the material.
However, if the binding strength of the material increases, which may occur when the material is compressed, it may result in that the material is stuck to the drums and leave the drums in blocks instead of a smooth stream of material. This results in a discontinuous feeding of material to the conveying device which, in turn, entails varying power consumption and feeding disruptions within the conveying device.
Thus, there is a need for improved feeding arrangements for feeding lignocellulosic biomass material such as annual plants to a treatment process and an improved system comprising such a feeding arrangement and a method for feeding lignocellulosic biomass material such as annual plants to a treatment process.